Structure and microstructure characterization of the mixed sesquioxides (Gd_1−xYb_x)₂O₃and (Gd_1−xHo_x)₂O₃prepared by sol–gel process

Abstract

Polycrystalline samples of (Gd1−xYbx)2O3 and (Gd1−xHox)2O3 (0.0 ≤x≤ 1.0) were synthesized by a sol–gel process. X‐ray diffraction data were collected and crystal structure and microstructure analyses were performed using the Rietveld refinement method. All samples were found to have the same crystal system and formed solid solutions over the whole range of x. For the system (Gd1−xHox)2O3, the cationic distribution over the two non‐equivalent sites 8b and 24d of the space group Ia were found to be random for all values of x. For (Gd1−xYbx)2O3, the distribution is random in the range 0.0 < x≤ 0.5 and preferential in the range 0.5 < x≤ 1.0. The lattice parameters are found to vary linearly with the composition x. Replacing Gd3+ and Yb3+, or Gd3+ and Ho3+, by each other introduces slight changes in relative atomic coordinates. Crystallite size and microstrain analyses were performed along different crystallographic directions and both are found to vary anisotropically with the composition parameter (x). The obtained values of microstrain are correlated with the distribution of the rare earth ions over the two cationic sites of the structure. The average crystallite size ranges from 45 to 144 nm and the root mean square (r.m.s.) strain from 0.018 to 0.409 × 10−2.

X‐ray diffraction analysis of powder and thin film of (Gd1‐xYx)2O3 prepared by sol‐gel process

“…This contradiction can be ascribed to the difference in the preparation method. In a previous work [19,22], we found a similar random distribution of cations in (Er 1-q Gd q ) 2 O 3 and (Gd 1-q Ho q ) 2 O 3 which is attributed to the small difference in cationic radii. Depending on the difference in cationic radii, a random distribution is obtained whenever the difference between the cationic radii is small (e.g Y 2-q Re q O 3 , Re = Dy and Ho, [15,25], and preferential one is obtained for longer difference in radii (e.g Eu 2-q Yb q O 3 [20]; Y 2-q Gd q O 3 [26] and Y 2-q Eu q O 3 [17] ).…”

“…Applying x-ray diffraction and magnetic susceptibility measurements, the cation ordering has been studied for a number of diluted magnetic semiconductors Y 2-x Ho x O 3 [15], Tm x Y 2-x O 3 [16], (YEu) 2 O 3 [17] and Y 2-x Gd x O 3 [18]. In a previous work we studied the mixed rare earth oxides ( [20,21] and (Gd 1-x Ho x ) 2 O 3 and (Gd 1-x Yb x ) 2 O 3 [22]. We have found random distribution of Er 3+ and Gd 3+ among the two different cationic sites, but preferentially for Eu 3+ and Yb…”

Effects of Phonon Confinement on Anomalous Thermalization, Energy Transfer, and Upconversion in Ln3+‐Doped Gd2O3 Nanotubes

“…[43,45] The energy difference between the maximum intensity peaks of the LMCT transitions for the two monitored wavelengths (248 and 255 nm, for S 6 and C 2 , respectively) is due to the shorter EuÀO bond length of the S 6 sites. [36] The excitation spectra of the Eu 3þ :Gd 2 O 3 nanocrystals resemble that of the microcrystals although a blue-shift of the LMCT band relative to the bulk materials is observed (Fig. S7A,B (SI)).…”

“…Given the n value and the structural Gd 2 O 3 data, [36] R 0 will be estimated. Figure 5A-C display the I(S 6 ), n, and R 0 values for Gd 2 O 3 :Eu 3þ nanotubes (0.16%, 1.00%, 3.30%, and 6.60%), nanorods, and microcrystals.…”

157-nm Resist Material Design for Improvement of Its Transparency Using Highly Precise Theoretical Calculation

“…The different methods of preparation of nanosize pure and mixed rare earth sesquioxides are described in the literature, e.g. sol-gel [11], spray pyrolysis [12], hydrogen plasma-metal reaction [13], colloidal precipitation route [10] and controlled hydrolysis [14]. To obtain nanosized Yb 2 O 3 /Y 2 O 3 we used high energy ball milling (HEBM).…”